Conventional compressors have various disadvantages, particularly when it comes to applications, such as gas compression for medical use. For example, relatively large, heavy, noisy and inefficient compressors are not suitable for medical applications where using oil is prohibited in the gas compression systems. Furthermore, in areas such as dental clinics and hospitals, quiet gas compressors are preferable. There is, therefore, a need in the art for quiet compressors with simple oil-free designs without relatively complicated timing and valve connections.